Height level control for sheets being stacked



Aug. 6, 1957 c. L vANslcKLE 2,801,756

HEIGHT LEVEL coNTRoL FOR SHEETS BEING sTAcxED Filed June 14. 1956INVENTR CALVIN L. vANslcKLE p 2,801,756 Imatented Aug. 6, 1957 HEIGHT`LEVEL CONTROL lFOR SHEETS BEING l STACKED Calvin L. Vansickle, Dundas,Ontario, Canada, assigner to Dominion Foundries and Steel Limited,Hamilton, Ontario, Canada Application'lune 14, 1956, Serial No. 591,324

2 Claims. (Cl. 214-6) This invention relates to a device forautomatically controlling the height level of stacked steel sheets andthe like and wherein the stack is formed by successively placing sheetsupon the top of the stack as the sheets are delivered from sheetshearing apparatus, as used in steel strip mills.

In standard practice lengths of steel strip continuously travel to theshearing apparatus where the are sheared to produce sheets of desiredsize, the sheets then travelling upon a conveyer belt or the like forsuccessive stacking delivery unto the top of a stack of sheets carriedupon a vertically moveable platform which is manually controlled indownward movement, the top of the stack being maintained at a levelslightly below the plane of sheet delivery from the conveyer to the `topof the stack and whereby the delivered sheets only have a short drop,irrespective of the number of sheets in stack.

In the foregoing arrangement the stack supporting platform is generallymounted upon the ram of a hydraulic lift, the platform being loweredthrough the manual ma nipulation of a valve mechanism controlling thebleeding of hydraulic iluid from the lift; and the object of thisinvention is to provide a pneumatic arrangement automatically actuatedby the height of the stack of sheets on the platform, and whichactuation controls the bleeding of fluid from the platform supportinglift whereby the platform gradually lowers in ratio to the building upof the height of the stack to maintain the top of the stack at thedesired sheet reception level.

A further object of the invention is to so arrange the pneumatic controlthat it consists of a source of air under pressure and from which air ispiped to be ejected in the direction of the side of a stack of sheetsbeing built up upon a stack carrying platform, the ejected air streamnormally having an unobstructed flow across the top face of the topsheet and the pneumatic control devised to operate the hydraulic liftduid bleeding valve mechanism under changes of air pressure in thecontrol; such changes in air pressure being brought about by relativelyslight changes in back pressure in the air pipe delivering air forejection and resulting from the building up of one or several sheetsupon the top of the stack whereby an obstruction against the freeejection of air is constituted and sets up a back pressure to actuatethe pneumatic control and so lower the platform to a point wherein thetop sheet of the stack is below the path of the ejected air stream andhas ceased to be an obstruction.

With the foregoing and other objects in view, as shall appear, theinvention consists of a control device constructed and arranged all ashereinafter more particularly described and illustrated in theaccompanying drawing in which the gure is a schematic view of theinvention as used in governing the height level of stacked steel sheets.

In general strip mill practice, the sheared to size steel sheets aredelivered on a conveyor (not shown) to be successively dropped unto thetop of a stack of sheets 2 being built up; the space within which thestack is formed being bounded by a suitable open topped enclosure 3 andthe stack carried upon a platform 4 mounted upon a ram 5 of a hydrauliclift cylinder 6. To move the ram upwardly fluid is injected into thecylinder, as through the pipe 7 which is valve controlled in the usualmanner. To permit the ram to lower, iluid is bled from the cylinderthrough an ejection pipe 8 and in prior practice the bleeding of uid wasmanually controlled by an operator who maintained the top sheet of thestack 2 at the desired level.

In this invention the bleeding of fluid from the cylinder through thepipe 8 is under the control of a valve 9 actuated by a solenoid 10energized by an electrical circuit 11; the actuation of the valve 9being controlled by fluctuations in air pressure in a pipe deliveringair to an air jet nozzle directed towards the top of the sheet stack 2,as shall now be described.

The air jet nozzle 12 is carried by one of the sides of the stackenclosure 3 and at a height substantially in line with the top face oredge of the top sheet of the stack, the nozzle being arranged tonormally direct a jet of air across the top face of the top sheet.Compressed air is fed to the nozzle from any suitable source and througha standard pressure regulator 13 and volume regulating valve 14 and fromwhere it passes through piping 15 to the nozzle.

A branch pipe 16 extends from the piping 15 to an air pressure actuatedswitch 17 controlling the electrical circuit 11, the switch beingdesigned and adjusted to operate under comparatively slight changes inair pressure in the branch pipe 16.

Operation When the top sheet of the stack 2 is at the required level airejection through the nozzle 12 is unobstructed. However, when additionalsheets are added to the top of the stack their side edges form anobstruction against free air ow from the nozzle, thus causing a slightback pressure in the piping 15 and branch pipe 16, which back pressureis sufficient to close the air pressure switch 17. Closure of the switch17 energizes the solenoid 10 to open the valve 9 and permit `fluid tobleed from the cylinder 6 through the pipe 8, whereupon the ram 5gradually lowers until the side edges of the several top sheets arebelow the path of air ejection from the nozzle. Immediately this occursthe back pressure in the piping 15 and branch pipe 16 is relieved withthe resultant` reduction of air pressure against the diaphragm 18 of theair pressure actuated switch 17 and permits the switch to open under thepressure of the spring 19. The consequent de-energization of thesolenoid 10 allows the plunger 20 to move downwardly and close the valve9 to cut od passage of fluid being bled from the hydraulic cylinder 6.As further sheets are delivered to the stack 2 the stack loweringoperation repeats. To provide for any desired height adjustment theportion 15A of the piping is made of ilexible material to permitadjustment of the nozzle 12 in the stack enclosure.

What I claim as my invention is:

l. In a device for controlling the height level of a stack of sheetscarried upon a downwardly moveable platform supported by a hydraulichoist and wherein the stack is built up by successively placing sheetsupon the top of the stack and the platform lowered by bleeding fluidfrom the hoist; a source of compressed air and air piped therefrom to beejected as an air stream at a predetermined stack tcp level and normallyflowing substantially across the top of the stack, means controlling thebleeding of uid from the hoist and actuated for the bleeding of fluid byback pressure against the free flow of the piped air and which backpressure is produced by retardation of the ow of the ejected air streampressure actuated switch being connected to the piped through itsimpingement against the top portion of the air and operable under backpressure against the free side of the stack of sheets as they are beingbuilt flow of the piped air.

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2. A device as claimed in claim 1, wherein the means 5 References Cid inthe file 0f thlS patent for bleeding uid from the hoist comprises asolenoid UNITED STATES PATENTS actuated valve, an electric circuit tothe solenoid actuated valve, an air pressure actuated switch in thecircuit and controlling energization of the solenoid, the air 2,247,466Baker et al. July 1, 1941 2,323,174 Wikle June 29, 1943

